1. Field of the Invention
The present invention generally relates to circuit breaker panelboard installations and, more particularly, is concerned with an improved circuit breaker switch actuating assembly in a circuit breaker panelboard.
2. Description or the Prior Art
Circuit breaker installations wired to major lighting, heating and electrical equipment in industrial facilities are typically enclosed by panelboards to provide protection of and restrict unauthorized access to the circuit breaker switches. In a typical panelboard installation, the switches are parts of modules arranged in a pair of parallel vertical columns. The "on" and "off" positions of the switches in one column of modules are opposite to the "on" and "off" positions of the switches in the other column of modules.
One prior art circuit breaker panelboard for enclosing the columns of circuit breaker modules includes a rear housing defining a cavity, and a front cover hingedly mounted to the rear housing for opening and closing relative thereto. The rear housing supports the circuit breaker modules in the pair of parallel columns in the cavity. Thus, the circuit breaker switches are thereby also arranged in the pair of parallel columns. The front cover has a plurality of closely-spaced holes arranged in a pair of vertical columns. The holes in the vertical columns are disposed in general alignment with the switches of the circuit breaker modules in the pair of vertical columns.
Also, the panelboard includes a plurality of operating members rotatably mounted through the plurality of closely-spaced holes of the front cover. Therefore, the operating members are arranged in a pair of vertical columns corresponding to the pair of vertical columns of the holes. One operating member is provided for each circuit breaker switch. Each operating member basically includes an elongated shaft rotatably mounted through a respective one of the holes in the front cover, a lever or handle attached to an outer end of the shaft and thereby disposed on the exterior side of the front cover where it can be gripped by a user's fingers, and a bifurcated trip arm attached to an inner end of the shaft and thereby disposed on the interior side of the front cover. The bifurcated trip arms are disposed at the same angular orientation on the elongated shafts of the operating members.
The bifurcated trip arm of each of the operating members is releasably coupled directly with one of the circuit breaker switches. By rotating the handle of an operating member in one direction, the respective one switch is moved linearly and arcuately from an "on" position to "off" position, whereas by rotating the handle of the operating member in the opposite direction the one switch is moved linearly and arcuately in reverse from the "off" position to the "on" position. The handles of the operating members in one column must be rotated in a direction opposite to the direction in which the handles of the operating members in the other column must be rotated in order for all circuit breaker switches of both columns of modules to move either to their respective "on" positions or to their respective "off" positions. To protect the operating members from unauthorized movement, latches are typically mounted to the front cover for use in locking the handles of the operating members at the desired one of their "on" or "off" positions.
There are several major drawbacks with a panelboard having the above-described construction. One drawback is that due to the closeness of adjacent operating members in each of the columns thereof, it is difficult to easily and quickly grip a desired one of the handles in order to move a selected one of the circuit breaker switches between its "on" and "off" positions.
Another drawback is that due to the closeness of the holes in the front cover which mount the operating members, stresses that are normally induced in the portions of the front cover surrounding the mounting holes tend to concentrate at these front cover portions and initiate cracks which can propagate and cause premature fractures of the front cover between the holes. Such fractures can interfere with properly functioning of the operating members and integrity of the cover and so typically necessitate replacement of the front cover and operating members of the panelboard.
Consequently, a need exists to provide an improvement of the construction of the above-described prior art circuit breaker panelboard which will eliminate the above-described drawbacks of the prior art without introducing new ones in their place.